EP0165736A2 - Injektionssynchronisierter RF-Oszillator und Verfahren zum Erzeugen von RF-Energie - Google Patents

Injektionssynchronisierter RF-Oszillator und Verfahren zum Erzeugen von RF-Energie Download PDF

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Publication number
EP0165736A2
EP0165736A2 EP85303928A EP85303928A EP0165736A2 EP 0165736 A2 EP0165736 A2 EP 0165736A2 EP 85303928 A EP85303928 A EP 85303928A EP 85303928 A EP85303928 A EP 85303928A EP 0165736 A2 EP0165736 A2 EP 0165736A2
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EP
European Patent Office
Prior art keywords
frequency
oscillator
source
perturbation
resonance frequency
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP85303928A
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English (en)
French (fr)
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EP0165736A3 (de
Inventor
Robin Michael Braun
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Plessey South Africa Ltd
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Plessey South Africa Ltd
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Publication date
Application filed by Plessey South Africa Ltd filed Critical Plessey South Africa Ltd
Publication of EP0165736A2 publication Critical patent/EP0165736A2/de
Publication of EP0165736A3 publication Critical patent/EP0165736A3/de
Withdrawn legal-status Critical Current

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03L—AUTOMATIC CONTROL, STARTING, SYNCHRONISATION OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES
    • H03L7/00—Automatic control of frequency or phase; Synchronisation
    • H03L7/24—Automatic control of frequency or phase; Synchronisation using a reference signal directly applied to the generator

Definitions

  • THIS INVENTION relates to an injection locked RF oscillator, and to a method of generating RF energy.
  • the resonance frequency of an RF source may be affected by a number of factors.
  • a difficulty hitherto experienced with injection locking of an RF source is that, to increase the lock range - i.e. the range of resonance frequencies over which the system will hold lock one lock has been acquired - the power of the injected signal has to be increased.
  • the injected power required to enable a system to hold lock in most applications was such as to render injection locking impractical as a means of frequency stabilizing an RF source.
  • an injection locked RF oscillator which comprises :
  • Said parameter may be the current consumption of the RF source.
  • the RF source may include a two-terminal negative resistance device, e.g. a Gunn diode.
  • the oscillator may further comprise means for sweeping the RF source through its frequency range upon swith-on, until injection lock has been acquired.
  • the oscillator may further comprise a perturbation generator for causing a perturbation in the resonance frequency, said sensing means being in the form of detecting means for detecting the resulting variation in said parameter in relation to the variation in the resonance frequency, and the control means being operative in respomse to the detecting means to provide a control signal for changing the resonance frequency towards the lock frequency.
  • the perturbation generator may be in the form of an oscillator for causing continuous sinusoidal perturbation, at a perturbation frequency, of the resonance frequency, the detecting means comprising means for detecting a sinusoidal variation at the perturbation frequency in said parameter.
  • the invention extends to a method of generating RF energy, which comprises :
  • reference numeral 10 generally designates an injection locked microwave oscillator, the oscillator comprising a variable frequency microwave source 12 which could have a frequency of, say, about 35GHz, a microwave reference oscillator 14, and a circulator 16.
  • the circulator 16 is arranged to inject the output of the reference oscillator 14 into the source 12, whilst passing the output of the source to an ouput port 17.
  • the microwave source 12 comprises a waveguide cavity resonator 18 having a Gunn diode 20 and a varactor 22 mounted therein in conventional manner.
  • the requisite bias voltage V b is applied to terminal 24 of the Gunn diode 20 via a dropper resistor 26.
  • the terminal 24 is connected to the input of an amplifier 28 which is operative to sense the voltage on the terminal 24, and to provide a dc output which varies in accordance with the current consumption I o of the microwave source.
  • the oscillator 10 further comprises a perturbation oscillator 30 whose output is coupled to terminal 32 of the varactor 22 via a coupling capacitor 34.
  • the oscillator 30 would typically have a frequency of about 10kHz.
  • the oscillator 10 further comprises a narrow band filter 36 whose centre frequency corresponds to the frequency of the perturbation oscillator 30, a phase detector 38, an envelope detector 40, a loop amplifier 42, a sweep-and-lock circuit 44, and a pause circuit 46, these being interconnected as shown in the drawing.
  • the sweep-and-lock circuit 44 operates to apply a ramp voltage to the terminal 32 of the varactor 22, thereby sweeping the source 12 through its frequency range.
  • the output of the reference oscillator 14 is continuously injected into the cavity 18 via the circulator 16. Initially, the source 12 will oscillate in the free-running mode at a free-running or resonance frequency f o which is determined by the voltage applied to the terminal 3.2 and which differs from the frequency f i of the reference oscillator 14.
  • the source locks onto the reference signal, whereupon the frequency of the source 12 is determined by the reference frequency fi and no longer by the voltage applied to the terminal 32.
  • the current consumption I o of the source 12 will rapidly increase. This rapidly increasing current is detected by the pause circuit 46, which then operates to hold or lock the sweep-and-lock circuit 44 via its input 48, although the output of the circuit 44 can still be controlled by the application of a signal to its input 50.
  • the ability of the source to lock onto the injected signal depends on various factors and can be expressed as follows, namely that injection locking will occur if
  • the capture range as well as the lock range for such a system is twice the maximum value of ⁇ f.
  • the capture range is the range of frequencies over which the system will capture lock
  • the lock range is the range of frequencies over which the system will hold lock, once lock has been acquired.
  • the effect of the sinusoidal modulation signal applied by the perturbation oscillator 30 to the varactor 22 is to cause a sinusoidal variation of the current consumption I o .
  • This is illustrated in Figure 2, where the curve A represents the instantaneous output of the perturbation oscillator, and the curve A' the instantaneous value of the current consumption I o - that is, where the frequency f o is less than the frequency fi. If the frequency f o is greater than the frequency fi, the output of the perturbation oscillator and the instantaneous value of the current consumption I o would be as illustrated by the curves B and B' respectively.
  • phase of I o with respect to the modulation signal is 0° or 180 0 depending on whether fi is less than or greater than f o
  • amplitude of the sinusoidal component of 1 0 depends on the slope of the I 0 versus ( ⁇ f curve.
  • the operation of the phase detector 38 is such that its output is high or low depending on whether the output of the filter 36 is in or out of phase with the output of the perturbation oscillator 30.
  • the envelope detector 40 is operative to provide an output whose magnitude corresponds to the amplitude of the sinusoidal component of I o .
  • the loop amplifier 42 is operative to provide inverting or non-inverting amplification of the output of the envelope detector 40, the sense of amplification depending on whether the output of the phase detector 38 is high or low.
  • the output of the sweep-and-lock circuit 44 in response to the output of the loop amplifier 42 is such as to increase the resonance frequency f o of the source 12 when the output of the filter 36 is in phase with that of the perturbation oscillator 30, and to decrease the resonance frequency when the two outputs are 1.80° out of phase.
  • the microwave reference oscillator 14 and the circulator 16 are done away with and replaced by a sub-harmonic reference oscillator 52 (shown dotted) whose output is injected into the source 12 via the terminal 24.
  • the reference oscillator may, in this event, conveniently be a frequency stable crystal controlled oscillator. Due to the non-linear characteristic of the Gunn diode, harmonics of the reference frequency are generated, and injection locking takes place with respect to one of these harmomics.
  • the ratio of power (Pi) injected at the relevant harmonic frequency to that (P i ') injected at the fundamental frequency is about equal to the square of the ratio of fundamental frequency (f i ) to the harmonic frequency (approximately f o )
  • the harmonic number
  • the lock range, and thus also the capture range of an oscillator with sub-harmonic injection is reduced by a factor of n in comparison with that of an oscillator with fundamental injection, with the same injected power.
  • the lock range is effectively extenced to the entire tuning range of the oscillator.
  • the loss in capture range is easily compensated for by the sweep generator forming part of the sweep-and-lock circuit 44.
  • the oscillator 10 can, for example, be used in a pulsed radar system.
  • One problem with pulsed oscillators is that heating effects during the period of the ulse cause the frequency to shift in an uncontrolled way during the pulse. This effect is also known as chirp. The result is that the pulse is distorted and range resolution as a result degraded.
  • the oscillator 10 may be used in a pulsed system whose pulse rate is at least twice as high as the band-pass of the external control loop constituted by items 36, 40 and 42. This loop would then cope with the environmental effects causing frequency change, while the frequency during the pulse would be controlled by the injection lock process.
  • the frequency of the reference signal f j may be kept constant during the pulse and the pulse would then have a chirp of 0.
  • fi may be chirped in a controlled way, in which event the locked source will follow fi, giving a controlled chirp pulse with advantages to range resolution.
  • reference numeral 10.1 generally indicates a microwave oscillator which is similar to the one shown in Figure 1, the same reference numerals being used to indicate the same parts.
  • the oscillator 10.1 differs from the oscillator 10 in that the phase detector 38 and the envelope detector 40 are substituted by a multiplier 60 and a low pass filter 62. (It will be appreciated that the low pass filter 62 may form an integral part of, for example, the loop amplifier 42).
  • the multiplier 60 is operative to multiply the instantaneous values of the outputs of the perturbation oscillator 30 and the amplifier 28 respectively. The output of the multiplier 60 is fed via the low pass filter 62 to the loop amplifier 42.
  • An oscillator according to the invention can also be used as a self-mixing receiver.
  • a configuration suitable for this purpose is illustrated in Figure 4, where reference numeral 10.2 generally indicates a microwave oscillator which is similar to the one shown in Figure 1, the same reference numerals being used to indicate the same parts.
  • Such a configuration is also generically referred to as an autodyne configuration. It provides a signal which is the mixing product of the microwave source's own signal and another signal impinging on the source.
  • the product signal (IF) is collected from the power supply terminal 24 through the use of an extractor circuit 70 (of a type known in the art) which is connected between the terminal 24 and the power supply V b .
  • an extractor circuit 70 of a type known in the art
  • the frequency of the source 12 in the Figures 1, 3 and 4 embodiments may be controlled by controlling the power supply voltage to the Gunn diode 20.
  • the varactor 22 can be omitted and the output of the sweep-and-lock circuit 44 used to regulate the power supply feeding the Gunn diode 20, and in this manner control the frequency of the source 12.

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  • Stabilization Of Oscillater, Synchronisation, Frequency Synthesizers (AREA)
EP85303928A 1984-06-05 1985-06-04 Injektionssynchronisierter RF-Oszillator und Verfahren zum Erzeugen von RF-Energie Withdrawn EP0165736A3 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ZA844213 1984-06-05
ZA844213 1984-06-05

Publications (2)

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EP0165736A2 true EP0165736A2 (de) 1985-12-27
EP0165736A3 EP0165736A3 (de) 1987-05-27

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EP85303928A Withdrawn EP0165736A3 (de) 1984-06-05 1985-06-04 Injektionssynchronisierter RF-Oszillator und Verfahren zum Erzeugen von RF-Energie

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US (1) US4631497A (de)
EP (1) EP0165736A3 (de)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4730169A (en) * 1986-08-14 1988-03-08 Hughes Aircraft Company Injection locking and tuning circuit for microwave diode oscillator
US9099956B2 (en) 2011-04-26 2015-08-04 King Abdulaziz City For Science And Technology Injection locking based power amplifier
US9445729B2 (en) 2012-07-20 2016-09-20 Resmed Sensor Technologies Limited Range gated radio frequency physiology sensor
TWI473441B (zh) * 2012-12-10 2015-02-11 Univ Nat Taiwan 接收機、訊號解調模組及其訊號解調方法

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4099144A (en) * 1976-04-26 1978-07-04 Nippon Telegraph & Telephone Public Corp. Injection-locked ultra-high frequency solid-state oscillator
EP0164994A2 (de) * 1984-06-05 1985-12-18 Plessey South Africa Limited RF-Oszillator und Verfahren zum Erzeugen von RF-Energie

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2972720A (en) * 1957-09-24 1961-02-21 Westinghouse Electric Corp Automatic frequency control apparatus
US3534284A (en) * 1967-11-15 1970-10-13 Bell Telephone Labor Inc Automatic phase-locking circuit
US3534285A (en) * 1968-06-19 1970-10-13 Honeywell Inc Digital phase control circuit for synchronizing an oscillator to a harmonic of a reference frequency
US3832713A (en) * 1973-03-01 1974-08-27 Us Navy Microwave phase shifting apparatus
US3878474A (en) * 1974-06-17 1975-04-15 Bell Telephone Labor Inc Phase locked loop
CA1111114A (en) * 1978-08-31 1981-10-20 Trevor W. Tucker Microwave frequency division by phase locked loops

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4099144A (en) * 1976-04-26 1978-07-04 Nippon Telegraph & Telephone Public Corp. Injection-locked ultra-high frequency solid-state oscillator
EP0164994A2 (de) * 1984-06-05 1985-12-18 Plessey South Africa Limited RF-Oszillator und Verfahren zum Erzeugen von RF-Energie

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
JOURNAL OF PHYSICS E, vol. 10, no. 12, December 1977, pages 1193-1207, London, GB; A. SEPTIER et al.: "Microwave applications of superconducting materials" *
PROCEEDINGS FOURTH BIENNIAL CORNELL ELECTRICAL ENGINEERING CONFERENCE, Ithaca, New York, US, 14th-16th August 1973, pages 43-51; D.N. McQUIDDY et al.: "Airborne radar applications for solid state microwave diode sources" *

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Publication number Publication date
EP0165736A3 (de) 1987-05-27
US4631497A (en) 1986-12-23

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Inventor name: BRAUN, ROBIN MICHAEL